Spanish authorities said Tuesday they are investigating the elder Assad for money laundering. They seized 503 properties belonging to him and his relatives. The collection of country estates, holiday homes, luxury apartments and a farm is worth €691 million ($740 million), they said.

Rifaat Al Assad, 79, was vice president of Syria in the 1980s when his brother and Bashar's father -- Hafez -- ruled the country.

He was exiled in 1984 for attempting to seize power while Hafez recovered from heart problems. He has mostly lived in exile in Europe since then, making a second futile attempt to seize power in 2000 when Hafez died.

The investigation in Spain includes 16 individuals associated with Assad, including two wives, six of his children and one Spanish citizen who allegedly administered Assad's assets in the country.

Officials in Spain say Assad may have taken as much as $300 million from Syrian state coffers for personal gain.

Rifaat Al Assad has also lived in France, whereauthorities investigated him in 2013 for embezzlement of Syrian funds and seized €90 million ($95 million) of real estate belonging to his family.Those assets were located in France, Curacao, Luxembourg and Liechtenstein.

In Spain, almost all of Assad's properties are in the coastal city of Marbella and its luxury yacht marina, Puerto Banus.